Study Examines Sunlight, Seasonal Blahs

Ohio State University researchers found the brains of mice shrink when deprived of sunlight, which they say might provide a clue about why humans get the winter blahs.

If humans' brains similarly shrink without sunlight exposure, it could be physical evidence of depression some people complain about when daylight decreases, said Leah Pyter, a doctoral student studying neuroscience at Ohio State University.

The study, published in a recent issue of The Journal of Neuroscience, attempts to show how seasonal changes could affect brain structure and function.

However, to test Pyter's theory on humans, subjects would have to be deprived of light and have their brains dissected to measure results.

Pyter and her adviser, Randy Nelson, think the shrinking in mice could be the result of fewer brain cells being created during short days in the area of the brain involved with memory and learning, called the hippocampus. Nelson, a psychology and neuroscience professor, co-authored the study.

The idea that shrinking brains contributes to season affective disorder seems plausible because previous research linked such seasonal disorders to the hippocampus, said Dr. Judy Stange, senior research director at the National Mental Health Association in Alexandria, Va.

About 6 percent of Americans suffer from seasonal affective disorder during winter months, she said.

The hippocampus seems to produce melatonin, a hormone that may cause depression, at increased levels when humans are exposed to longer periods of darkness, Stange said.